3OTK:
reference: Structural and mechanistic characterization of leukocyte-type core 2 beta1,6-N-acetylglucosaminyltransferase: a metal-ion-independent GT-A glycosyltransferase., Pak JE, Satkunarajah M, Seetharaman J, Rini JM, J Mol Biol. 2011 Dec 16;414(5):798-811. Epub 2011 Oct 26. PMID: 22056345

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).